The ABCs of DEX Z-Code Identifiers

The DEX Z-Code™ Identifier is a unique 5-character alpha-numeric code associated with certain molecular diagnostics (MDx) tests and is used by certain payers as an adjunct to non-specific CPT codes.

This code is assigned within the Change Healthcare’s DEX Diagnostics Exchange (DEX) based on the uniqueness of each test being registered. This code, submitted on a claim, in addition to the CPT code, provides greater clarity to help ensure that both payers and providers clearly understand which test is being ordered, performed, and billed.

To get started, your lab must follow each of the steps outlined below:

Step 1: Register your lab

Step 2: Request sharing

Step 3: Search for a DEX Z-Code

Already registered for DEX Z-Code™ access? Click here to request a current report of Quest-assigned Z-Code™ Identifiers.

Step 1: Register your lab

From the DEX Homepage, click on the button to “Register as a Lab or Hospital” and follow the instructions to provide all required laboratory information. After accepting the Change Healthcare’s Terms of Use, submit the application. You will be contacted by Change Healthcare once your application has been approved and you are active in DEX.

Step 2: Request Sharing

To gain immediate access to all Quest assigned DEX Z-Code Identifiers, you must request sharing with Quest. After you’ve logged into DEX, click on the “Labs & Manufacturers” tab in the center of the screen.

On the next screen, browse for “Quest Diagnostics” using the search bar. When you see Quest Diagnostics as the parent laboratory, click on the “+” to bring up a list of all Quest facilities. Select any facility to open a page of general lab details.

On the lab details page, click on the “Request Sharing” button in the upper-right corner. When prompted, select “Send Request”.

You now have immediate access to all DEX Z-Code™ Identifiers assigned to Quest.

Step 3: Searching for Codes

After completing the first two steps, you will have access to all of the DEX Z-Code Identifiers assigned to Quest. You can log in to DEX and browse by Lab Tests or by Labs & Manufacturers as shown in the screenshot below.

To browse by Lab Tests, you will enter a specific test name or orderable test code in the search bar.

For example, if you are looking for the DEX Z-Code for Quest’s BRCAvantage, Comprehensive Test offering, simply search using the orderable test code, 91863, and then click on the test to see details.

The DEX Z-Code will be found in the middle of the page, but the DEX Z-Code and CPT codes have been whited out in the example below for proprietary reasons.

To browse by Labs & Manufacturers, enter Quest Diagnostics and choose a facility via the (+) to bring up a list of Quest facilities. Select the facility and you will bring up a list of tests performed at that facility. When you see the test you need, click for details.


If you have any additional questions or need support, please contact Quest Diagnostics via our Z-Code Request email at

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